Electrode for electron discharge devices



INVENTOR T HEY WALTER 1.. KRAHL W. L. KRAHL Filed Feb. 12,

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Nov. 28, 1933.

ELECTRODE FOR ELEcTRoN DISCHARGE DEVICES Fig. 3.

Patented Nov. 28, 1933 ELECTRODEY- FOR 'ELEc'rRoN DISCHARGE y V DEVICES l p Y l Walter Louis Krahl, Montclair, N. J., assi'gnonfV by mesne assignmcntsyto Arcturus Developyment Company, Newark, N. J., a corporation'lof n Delaware Application Febuary 12, 1931. serial No. 515,226 11o claims. (crm-*275x This invention relates to electrodes for electron discharge devices and more particularlyy to the cathode and heater type therefor.`

It is a recognized fact that in heater type lof Y electron discharge devices that improvedresults are obtained by connecting the` cathode to the mid-point of the filament. This connection is usually accomplished by providing a center tap to the secondary of the lament transformer and connectingv this point to the cathode terminal of the tube socket, or by connecting a center tapped resistor across the secondary of the filament transformer and providing afconductor between the cathode terminal of the tube socket and center point of the resistor. v

One of the principal objects ofthe invention is to eliminate the necessity for center tapping or providing a potentiometer across the secondary of the filament transformer.,

Other objects of the invention are to obtain aVv positive flow of the filament current in a yportieri of the cathode; to avoidbending the filament,

wire further than a right-angle bend; to utilize filament wire ,of less length than .required-for hair-pin filaments; to enable the filament-to be readilyv assembled in the cathode; to -secure sim,- plicity of construction and. operation and to obtain other advantages and results .as may be brought out in the following description.

Referring to the accompanying drawing in which like numerals of reference indicate same parts throughout the severalviews:

Fig. 1 is an elevation of an electron 4disclriaijge device showing my invention applied thereto, the.

side of the anode nearest the observer being omitted so as to show the parts normally within the anode;

Fig. 2 is a vertical longitudinal section over the cathode showing the same on a larger scale than l illustrated in Fig. 1;

filament taken on line 3--3 of Fig. 2, looking in the direction of the arrows; .Y

Fig. 4 is an elevation of a modified construction of cathode with filament thereon; and

5 5 of Fig. 4.

In the specific embodiment of the invention Fig. 3 is a plan or end View of the cathode andV Fig. 5 is a longitudinal sectional View on line projecting upwardly therefrom and carryan anode 4, grid 5, cathode 6 and filament 7 as willi be understood by lthose 'versed in the art. Cer-L' tainof the supports are connected to suitable prongs in the base so as rto obtain electrical connection from the outside of the device to the elec-f trodes therein.k 'As here shown, a prong Sconynects with a support 9 4carrying the anode.

filament 7projecting-from the bottom of the cathode` which is connected to prong 14..

As more particularly shown in Figs. 2 and 3,.the

filament 7 is preferably formed from two lengths of wire which extend through the cathode properly insulated therefromfand from each other byl proper spacing or insulative coating, cr otherwise` f as well known in the art. The sections of the lila- `ment thus formed are preferably of'e'qual resistance. At the upper end of the cathode are preferably provided laterally extending ears 16, 17',-

shown as formed integrally with the cathode and bent radially outward from the end of said cathode,. one ear preferably being diametrically opvso posite-from the other ear.'l The upper endof each lengthof the vlament `7 is also bent laterally and one ofv these .bent ends 1.8"is attached to yone ear,16, vvhile the' other bentend 19 isattached to the other'ear 17.-:V .Attachment of thebent'ends to saidealrs'is accomplished in any desired manner, as by welding.

It vWill be; observed that lby bending the ears outwardly andbending the'zends of the filament sections outwardly thesame are` readily laccessibleffor Welding purposes. Itwill furthermore be observed that a circuit is thus obtained from one prong 12 through support 12',

to one section-of the filament 7 up to its kbent end 18 to ears 16 and then through the material forming the cathode to the other ear 17 and bent end 19 on the other filament section. The circuit then is completed through that section of the-lament 7 to itscsupport 15 and connected prong 13.

The construction described above accordingly obtains a mid-point connection for the filament whereiny the' filament circuit must of necessity pass through a portion of theV cathode and Will therefore unfailingly obtain equalpotential of the cathode and filament at the mid-point. In the manufacture of the tube, no further test is necessary than to see that the filament :'Willglow in order to determine if there is contact between the Y 2 sembly of the device is 'likewise very simple in that the filament sections can be dropped into the cathode very readily independent of each other and without `any tendency to rub against the in- 5 side of the cathode under tension as often occurs ing outwardly, said ears receiving the bent ends with hair-pin filament. This assumes importance Where the filament and cathode are protected from each other by an insulative coating, as the frictional Contact under tension may su'ice to expose the bare metal and result in a short circuit sooner or later.

In Figs. 4 and 5, a modified construction of cathode is illustrated, the same having vears 20, 21.

upstanding from the end thereof instead of bendof the filament sections transversely thereof, as clearly shown inFig. 4. The bent ends 18, 19

in this construction are welded or otherwise se' cured to the ears where they cross the same, and thus obtain positive contact for completing the filament circuit through a portion of the cathode. In these two figures now being described, the further feature is illustrated of increasing the path of the filament current in the cathode by slottransverse to the plan of the filament sections. By this construction one of the ears 20, projects from one of the bifurcations of the cathode while the other ear 21 projects from the otherbifurcation.' The slot 22 `may be made of any desired tion to the other. This construction will accord-v,

ingly obtain as nearly constant any equalization of the potential between the mid-pointof the filament and the cathode as ordinarily required for Y electron discharge devices.VV y

Obviously detail changes and modifications may be made in the construction and use of my improved electron device without departing from the spirit or scopeV of the invention, and I do not wish to be understood as limiting myself tothe exact construction shown or describedy exceptas iset forth,.i n the following claims when construed U fin the light of the prior art.

filament for heatingsaid cathode, said filament comprising a plurality of sections having. ends ce l ting the cathode as at 22 in a longitudinal planv Vwith Vone of said ears on each bifurcation.

thereof connected at separated points to the cathode, said cathode enclosingV said filament sections.

. 2.`In combination with a tubular cathode, a filament for heating saidcathode, said filament comprising a plurality of sections, each section having one end thereof secured to the cathode With the ends of the sections mechanically separate so as to complete the electric circuit through va portion of the cathode, said cathode enclosing said filament sections. Y

3. In combination with a cathode having separated ears thereon, of av filament connected to said ears.

4. In combination with a cathode having separated ears thereon, a filament comprising sections, each section being secured individually to an ear.

5. In combination with a cathode having separated ears thereon, a filament comprising sections,.each section being secured individually -to an ear, the cathode foi'mingan electrical path completing the electric circuit from one filamentv section to another. i Y Y 6. In combination with a cathode, ears on the cathode projecting therefrom,jand filament sections each having bent ends 'engaging Vsaid ears for obtaining an electrical connection from each*V filament section to the cathode.

7.- In combination with a cathode, ears on the i' nection from each filament section' tothe cathode.` 8. In combination cathode projecting longitudinally therefrom'and with a cathode, ears onthev filament sections each having bent endsv engag-k ing said ears for obtaining anelectrical ccnnection from each filament section to the cathode.

9. In combination with a cathode, ears onl the cathode projectingtherefrom, and filament sec ears on 'each' bifurcation. A

10.V In'combination with ahcathode, ears on the I cathode projectinglongitudinally therefrom, and filament sections each having bent ends engaging` said ears'forobtaining an electricalccnnec'- f tion from each filament section to the cathode, 1. In combination with a tubular cathode,lay

said cathode having a portion of itself ybifurcated n WALTER LOUIS KRAHL.

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